Vehicles with a combustion engine comprise a tank system for storing liquid fuel. For such fuel tank systems, evaporation of hydrocarbon gas within the tank system is an issue. By means of an activated carbon filter, evaporated hydrocarbon gas of the tank system is bound. The tank system further comprises a duct line, for forwarding the hydrocarbons to an induction line for providing the combustion engine with filtered oxygen mixed with the hydrocarbons. Generally, the transport of the hydrocarbons from the active carbon filter to the combustion engine is evoked by a negative pressure within the induction line. For controlling a volumetric flow of the hydrocarbons, a purge valve is provided between the induction line and the active carbon filter.
In some cases, the negative pressure of the induction line is not big enough for assuring a predetermined volumetric flow of the hydrocarbons. In order to overcome this drawback, a purge pump is provided between the active carbon filter and the purge valve. The purge pump is configured for the suction of fresh air via a separate air duct line through the active carbon filter, wherein, by these means, the fresh air is mixed with the hydrocarbons within the active carbon filter. The purge pump is further configured for the transport of the hydrocarbon-air-mixture to the induction line of the combustion engine. Generally, the purge pump is configured as a continuously operating pump, forwarding the hydrocarbon-air-mixture with a constant or at least substantially constant volumetric flow. In this case, the volumetric flow is still controlled by the purge valve. This has the advantage that a tank system architecture without such purge pump just needs minor adjustment for the integration of a purge pump. For ensuring a reliable continuous operation of the purge pump, standard purge pumps are operated by a brushless DC motor.
Besides the afore-mentioned advantages, the usage of a tank system architecture comprising a purge pump with a brushless DC motor has a major disadvantage. When a connection between a brushless DC motor and a control unit for controlling or operating the brushless DC motor is interrupted, due to mass inertia of an impeller of the purge pump, the brushless DC motor usually will continue spinning for a short period. In case of an accident, the purge pump would continue pumping explosive fluid towards the combustion engine or—in case the duct line is broken or detached from the purge pump or the induction line—the explosive fluid could possibly be pumped into the motor compartment, a rear compartment or the like of the vehicle.